Load email settings from a YAML configuration file

email.yml

# config/email.yml
---
test:
  :delivery_method: :test
  :url_host: 'localhost:3000'
development:
  :delivery_method: :smtp
  :host: "localhost:1025"
production:
  :delivery_method: :smtp
  :address: 'localhost'
  :port: 25
  

mail_settings.rb

# config/initializers/mail_settings.rb

email_settings = YAML.load_file("#{Rails.root.to_s}/config/email.yml")[Rails.env.to_s]

Rails.application.config.action_mailer.default_url_options = {
  host: email_settings.delete(:url_host) || "localhost:3000"
}

Rails.application.config.action_mailer.delivery_method = email_settings.delete(:delivery_method)
Rails.application.config.action_mailer.smtp_settings = email_settings